How to pass array of datetime64[ns] to pybind11 without copying

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I am trying to pass an array of datetime64[ns] into C++ using pybind11. For arrays of integers or floating point values, one can simply use the wrapper py::array_t<int64_t or double>.

Is there a dedicated type in pybind11 for datetime64[ns] in C++ side so that I can capture as py::array_t<DateTime>?

As a sub-optimal solution, it would be already a great improvement if I can instead pass the underlying storage of a datetime64[ns] array which is expected to be stored as an array of int64. Is there any light way (i.e., no copy) to pass this as an array of int64?

pybind11 numpy
1 Answers

It's not the most ergonomic, but you could probably use py::array_t<int64_t> as the pybind11 interface's type, and convert the array (without copy) like this:

In [1]: a = np.array([np.datetime64(x, 'ns') for x in range(10)])

In [2]: v = a.view(dtype=np.int64)

In [3]: v
Out[3]: array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9], dtype=int64)

In [4]: some_pybind_method(v)

There's a way to write a custom type conversion that does this transparently, but I'm not familiar with the required Python C-API needed for this.

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